Human rights in Kuwait have been eroding in the years since "Arab Spring" protests swept the region in 2011 as authorities have cracked down on dissent, rights group Amnesty International said in a report on Wednesday.

Kuwait, a Western-allied oil exporter, avoided the large-scale protests when some rulers in the region were overthrown, but citizens held large street protests in 2012 over changes to the electoral law.

While Kuwait allows more freedom of speech than some other Gulf Arab states, the emir has the last say in state affairs and the country has been cracking down on people suspected of trying to "undermine stability". The government has said it would strike with an "iron fist" against dissent.

The Kuwaiti information ministry had no immediate response to the report. "In the five years since a wave of popular protests swept across the Arab world we have witnessed a steady, relentless eroding of human rights in Kuwait as the authorities step up the clampdown on dissent," said James Lynch, deputy Middle East and North Africa director at Amnesty International.

"The government has a clear choice between allowing the country to slide into deeper repression or taking urgent steps to prove that its public commitments to human rights are more than just hollow promises," he said.

Amnesty said authorities were using a "web of vague and overly broad defamation laws" to crack down on freedom of expression, had shut media outlets and stripped some critics of their citizenship.

Amnesty said there had also been an increase in prosecutions over comments deemed "offensive" to the emir. Earlier this year, a court sentenced a human rights activist to three years in jail on charges of insulting the ruler.

Musallam al-Barrak, a former member of parliament, this year began serving a two-year term for a 2012 speech criticising an election law which he and other opposition politicians said was intended to prevent them getting power.